Field of the Disclosure
The invention relates to a method for making a WC-Co cemented carbide, the WC-Co cemented carbide made by the method, and cutting tools containing the WC-Co carbide.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Certain applications require materials exhibiting combination of both hardness and toughness. One of these applications is tooling industry which needs higher hardness of tool for cutting and higher toughness to sustain jerks and vibration during cutting. WC-Co is a widely used material in the tool industry. Improvement in attaining higher values of the combination of these properties is necessary in order to cut difficult substrates such as rock.
Tungsten carbide is a material that is formed by reacting tungsten and carbon. In its most basic form tungsten carbide includes only atoms of tungsten and carbon. Tungsten carbide (WC) has many desirable properties and is used for manufacturing cutting tools such as drilling/milling bits.
Tungsten carbide is often used in the form of an alloy with a matrix material such as another metal. Tungsten carbide cobalt (WC-Co) compositions are used where sintered tungsten carbide is described. A WC-Co material includes WC grains or particles dispersed in or alloyed with a Co matrix. Tungsten carbide cobalt can be described as a composition including a hard ceramic phase (WC) and a ductile metallic phase (Co) in which the hard ceramic phase is an alloy of the ductile metallic phase. Most commonly such carbide alloys are formed by thermally treating a mixture of a tungsten carbide powder and a metal powder and are sometimes characterized according to the grain size of the alloy.
Cutting tools for use in applications such as drilling rock need cutting surfaces having extreme hardness and toughness. Conventionally, hardness and toughness in drilling bit applications has been achieved by including additional materials of high hardness together with WC. This strategy substantially increases the costs of the cutting tool and requires complex manufacturing methods. The present disclosure describes a method for making a tungsten carbide cobalt material having low grain size and a desirable combination of hardness and toughness characteristics and its use for making cutting tools.
Drilling companies have used WC-based cemented carbides that are mixed with diamond particles in order to attain composites with higher hardness and toughness values. This approach (adding diamond reinforcements) in developing drilling materials is very expensive. The presented disclosure provides a technological route that result in alloys that retain their nano-grains which resulted in achieving an excellent combination of hardness and toughness which are both needed to achieve competitive drilling materials. Our comprehensive experiments and the analysis provide excellent insight into all possible options to synthesize these materials with the addition of commonly used grain growth inhibitors (VC and Cr3C2). We have explored most of the options in terms of adding different quantities of inhibitors and different quantities of the binding material. Additionally, we have explored the effect of consolidating these materials using different temperatures of SPS (1200° C. and 1300° C.).
It is now disclosed that the addition of different amounts and combinations of grain growth inhibitors to a basic WC-Co powder provides a refined microstructure thus improving hardness in combination with improving toughness.